He was angered by an alleged last-minute cut in their set time, managing to take a dig at Justin Bieber before trashing his guitar.

In a statement posted on the Green Day Facebook page, the band confirmed that Armstrong has entered rehab and that their set was not cut short. They said:

"Billie Joe is seeking treatment for substance abuse. We would like everyone to know that our set was not cut short by Clear Channel and to apologize to those we offended at the iHeartRadio Festival in Las Vegas. We regretfully must postpone some of our upcoming promotional appearances."